Topical Trimethoprim is effective against gram (-) and gram (+) bacteria except which gram negative bacteria?

Topical Trimethoprim is effective against gram (-) and gram (+) bacteria except which gram negative bacteria?

• A. Pseudomonas
• B. Escherichia coli
• C. Klebsiella
• D. Enterobacter

Answer: (A)

Topical trimethoprim works by inhibiting an enzyme needed to make folic acid in bacteria, which blocks DNA synthesis. This gives it activity against many gram-negative enteric bacteria and gram-positive organisms. However, Pseudomonas aeruginosa has intrinsic resistance to trimethoprim due to limited drug entry into the cell and other protective mechanisms, so it is not effectively targeted by topical trimethoprim. In contrast, organisms like Escherichia coli, Klebsiella, and Enterobacter are typically susceptible, which is why they’re listed as covered by topical trimethoprim.

Topical trimethoprim works by inhibiting an enzyme needed to make folic acid in bacteria, which blocks DNA synthesis. This gives it activity against many gram-negative enteric bacteria and gram-positive organisms. However, Pseudomonas aeruginosa has intrinsic resistance to trimethoprim due to limited drug entry into the cell and other protective mechanisms, so it is not effectively targeted by topical trimethoprim. In contrast, organisms like Escherichia coli, Klebsiella, and Enterobacter are typically susceptible, which is why they’re listed as covered by topical trimethoprim.